The following abbreviations are used in the application documents of the present application.
BG: (1→3)-β-D-glucan
EDTA: ethylenediamintetraacetic acid
PBS: phosphate buffered saline
Background arts of the present invention are described in the following.
It is described in Patent Reference 1 that a method for measuring BG, which comprises pre-treating a sample which may contain a BG mainly consisting of a triple helix structure, under a strong alkaline condition, to destroy or inactivate endotoxin alone or endotoxin and a factor G system reaction disturbing factor, which are possibly contained in the sample as reaction disturbing factors, followed by subjecting it to a Limulus reaction by a Limulus reagent. Additionally, it is described in “Example 3” of said reference that schizophyllan consisting of 100% triple helix structure is added to PBS (+) and Hanks' solution prior to the Limulus assay, and that each of 0.492 mM MgSO4 and 0.812 mM MgSO4 is contained in said PBS (+) and Hanks' solution.
Additionally, it is described in Patent Reference 2 that an alkaline earth metal halide in a pretreatment agent for endotoxin assay use is set to a range of from 0.005 to 0.05 mol/L, and an alkali metal halide is set to a range of from 0.05 to 0.5 mol/L. However, the concentration disclosed therein is concentration “in a pretreatment agent” and is not the final concentration when it is allowed to contact with a sample.
There is no description or suggestion in any of these references on a pretreatment in which an alkali metal sulfate and/or an alkaline earth metal sulfate is allowed to contact with a sample which is subjected to a Limulus assay, under such a condition that its final concentration becomes 20 mM or more.
Additionally, there is no description or suggestion also on a pretreatment in which an alkali metal halide and/or an alkaline earth metal halide is allowed to contact with a sample which is subjected to a Limulus assay, under such a condition that its final concentration becomes more than 0.4 M and equal to or lower than 1.2 M.
Patent Reference 1: JP-A-7-128337
Patent Reference 2: JP-A-6-70796